When Formtastic needs to find a handler for an input type (like `:string`), it uses a [Class Finder](http://www.rubydoc.info/github/justinfrench/formtastic/Formtastic/NamespacedClassFinder).

This object maps `:string` into a class name `StringInput` and tries to find it in a namespace like `Formtastic::Inputs`. You can customize this, by creating own ClassFinder that changes the class name or the namespace. For example you can have `MyClassFinder` that will for `:string` look up `MyNamespace::MyStringInput`.

This is useful for plugin authors like activeadmin and formtastic-bootstrap that have custom inputs in own namespace.

The default class finders are [InputClassFinder](http://www.rubydoc.info/github/justinfrench/formtastic/Formtastic/InputClassFinder) and [ActionClassFinder](http://www.rubydoc.info/github/justinfrench/formtastic/Formtastic/ActionClassFinder). Both look up the class name in all namespaced, configured in `Formtastic::FormBuilder.input_namespaces` and `Formtastic::FormBuilder.action_namespaces` settings.
